Organic electroluminescent device and method of manufacturing the same

ABSTRACT

The invention provides an organic electroluminescent device and a method of manufacturing the same which conveniently reduce or suppress the transfer of ionic impurities into a light-emitting layer, and reduce or prevent the light-emitting property in the light-emitting layer from degrading, which promotes life extension. An organic electroluminescent device includes a functional layer having at least a light-emitting layer between a first electrode and a second electrode. At least a part of the functional layer is formed of the inorganic ion exchange material added to the functional material to form the functional layer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of Invention

[0002] The present invention relates to an organic electroluminescentdevice and a method of manufacturing the same with an enhancedlight-emitting property by selective trapping and fixation of mobileions.

[0003] 2. Description of Related Art

[0004] Related art organic electroluminescent elements (hereinafter“organic EL elements”) using an organic substance in a light-emittinglayer can be used as a spontaneous emission display. A significant issuewith organic electroluminescent devices that have such organicelectroluminescent elements is the life extension of the elements. Thus,a technology to promote the life extension of the elements isadvantageous.

[0005] Accordingly, related art electroluminescent elements (organicelectroluminescent devices), in which a device to apply a voltage in adirection opposite to the emitting electric field is provided in adevice to apply a voltage between an anode and a cathode, is disclosedin Japanese Unexamined Patent Application Publication No. 9-293588, forexample. The provision of such devices allows, for example, theorientation polarization of a functional group, which is a part of theorganic compound composing the light-emitting layer when emitting, orthe ionic polarization of ionic impurities, to be reduced or suppressedin advance by applying a voltage to the opposite direction beforeemitting light for the first time, and allows ionic impurities (mobileions) to be prevented from being transferred and diffused into thelight-emitting layer. As a result, the light-emitting property could beprevented from degrading or such degradation could be reduced in thelight-emitting layer caused by the ionic impurities, and the lifeextension of the electroluminescent elements (organic electroluminescentdevices) could be promoted.

SUMMARY OF THE INVENTION

[0006] However, the electroluminescent element (organicelectroluminescent device) prevents the transfer of ionic impurities byits drive method, and prevents the light-emitting property fromdegrading in the light-emitting layer. Naturally, the drive system insuch an electroluminescent element (organic electroluminescent device)becomes complicated, and eventually brings about a new issue, which maycomplicate the construction of the device.

[0007] The present invention addresses the above and/or othersituations, and provides an organic electroluminescent device and amethod of manufacturing the same which can conveniently reduce orprevent the ionic impurities from transferring into the light-emittinglayer, and eventually reduce or prevent the light-emitting property fromdegrading in the light-emitting layer and promote life extension.

[0008] To address or achieve the above, the present invention providesan organic electroluminescent device including a functional layer havingat least a light-emitting layer between a first electrode and a secondelectrode. At least a part of the functional layer is formed by using afunctional material with an inorganic ion exchange material.

[0009] According to the organic electroluminescent device, at least apart of the functional layer is formed of an inorganic ion exchangematerial added to the functional material to form the functional layer.Thus, if ionic impurities are included in the functional layer with theaddition of the inorganic ion exchange material, the ionic impuritiescan be prevented from diffusing, or such diffusion can be reduced, intothe light-emitting layer by trapping and fixation onto the inorganic ionexchange material, and the degrading of the light-emitting property canbe reduced or prevented. Also, when the ionic impurities included ineach of the electrodes or other functional layers become mobile ions anddiffuse, the trapping and fixation onto the inorganic ion exchangematerial will reduce or prevent the ionic impurities from diffusing into the light-emitting layer.

[0010] Further, in the organic electroluminescent device, preferably,the functional layer has a carrier injection/transport layer, and thefunctional layer formed by adding the inorganic ion exchange material isa hole injection/transport layer functioning as the carrierinjection/transport layer.

[0011] When done this way, the mobile ions (ionic impurities) existingin the material to form the hole injection/transport layer will betrapped and fixated onto the inorganic ion exchange material. Thus, thelight-emitting property is prevented from degrading, or such degradationis reduced, in the light-emitting layer caused by the mobile ions.

[0012] Also, in this case, it is preferable that the inorganic ionexchange material be antimony pentoxide hydrate.

[0013] Antimony pentoxide hydrates have high selective absorption to Naions. If the Na ions exist in the material to form the holeinjection/transport layer, these Na ions can be satisfactorily trappedand fixated to prevent them from diffusing.

[0014] Further, in the organic electroluminescent device, the functionallayer formed by adding the inorganic ion exchange material may be thelight-emitting layer.

[0015] When done this way, even if the mobile ions (ionic impurities)diffuse into the light-emitting layer, they will be trapped and fixatedby the inorganic ion exchange material. Thus, the light-emittingproperty is prevented from degrading, or such degradation is reduced, inthe light-emitting layer caused by these mobile ions.

[0016] Further, in the organic electroluminescent device, the functionallayer may have a carrier injection/transport layer, and the functionallayer formed by adding the inorganic ion exchange material may be anelectron injection/transport layer functioning as the carrierinjection/transport layer.

[0017] When done this way, the mobile ions (ionic impurities) existingin the material to form the electron injection/transport layer will betrapped and fixated onto the inorganic ion exchange material. Thus, thelight-emitting property is prevented from degrading, or such degradationis reduced, in the light-emitting layer caused by these mobile ions.

[0018] The present invention provides another organic electroluminescentdevice including a functional layer having at least a light-emittinglayer between a first electrode and a second electrode, in which aninorganic ion exchange layer, formed of an inorganic ion exchangematerial, is provided between the first electrode and the secondelectrode.

[0019] According to the organic electroluminescent device, an inorganicion exchange layer is provided between the first electrode and thesecond electrode. Thus, if ionic impurities included in each of theelectrodes or functional layers, such as the hole injection/transportlayer, become mobile ions and diffuse, they will be trapped and fixatedby the inorganic ion exchange layer, preventing the light-emittingproperty from degrading, or reducing such degradation, caused by theionic impurities diffusing into the light-emitting layer.

[0020] Further, in the organic electroluminescent device, it ispreferable that the functional layer has a hole injection/transportlayer between the first electrode and the light-emitting layer, and theinorganic ion exchange layer be provided between the holeinjection/transport layer and the light-emitting layer.

[0021] When done this way, the mobile ions (ionic impurities) existingin the material to form the hole injection/transport layer will betrapped and fixated at the inorganic ion exchange layer. Thus, thelight-emitting property is prevented from degrading, or such degradationis reduced, in the light-emitting layer caused by these mobile ionsdiffusing into the light-emitting layer.

[0022] Further, in the organic electroluminescent device, it ispreferable that the functional layer has an electron injection/transportlayer between the second electrode and the light-emitting layer, and theinorganic ion exchange layer be provided between the electroninjection/transport layer and the light-emitting layer.

[0023] When done this way, the mobile ions (ionic impurities) existingin the material to form the electron injection/transport layer will betrapped and fixated at the inorganic ion exchange layer. Thus, thelight-emitting property is prevented from degrading, or such degradationis reduced, in the light-emitting layer caused by these mobile ionsdiffusing into the light-emitting layer.

[0024] The present invention also provides a method of manufacturing anorganic electroluminescent device that includes a functional layerhaving a light-emitting layer and a carrier injection/transport layerbetween a first electrode and a second electrode. The method includes:adding an inorganic ion exchange material to a functional material, andforming at least a part of the functional layer using the obtainedfunctional material.

[0025] According to the method of manufacturing an organicelectroluminescent device, at least a part of the functional layer isformed with the inorganic ion exchange material added to the functionalmaterial to form the functional layer. If ionic impurities are includedin the functional layer with the addition of inorganic ion exchangematerial, they will be trapped and fixated onto the inorganic ionexchange material, thereby preventing the light-emitting property fromdegrading, or reducing such degradation, caused by the ionic impuritiesdiffusing into the light-emitting layer. Also, when ionic impuritiesincluded in each of the electrodes or other functional layers becomemobile ions and diffuse, they will be trapped and fixated onto theinorganic ion exchange material, preventing the light-emitting propertyfrom degrading, or reducing such degradation, caused by the ionicimpurities diffusing into the light-emitting layer.

[0026] Further, in the method of manufacturing an organicelectroluminescent device, it is preferable that the functional materialwith the addition of the inorganic ion exchange material be disposed byejecting liquid droplets, to form the functional layer.

[0027] When done this way, it will be possible to precisely distributethe functional material with the addition of the inorganic ion exchangematerial at the desired location, and thus, for example, selectivelydistribute the inorganic ion exchange material corresponding to thelight-emitting layer's color.

[0028] The present invention also provides another method ofmanufacturing an organic electroluminescent device that includes afunctional layer having at least a light-emitting layer between a firstelectrode and a second electrode in which an inorganic ion exchangematerial is disposed between the first electrode and the secondelectrode to form an inorganic ion exchange layer.

[0029] According to the method of the manufacturing the inorganicelectroluminescent device, an inorganic ion exchange layer is formedbetween the first electrode and the second electrode. Thus, when theionic impurities included in each of the electrodes or the holeinjection/transport layer become mobile ions and diffuse, they will betrapped and fixated at the inorganic ion exchange layer, preventing thelight-emitting property from degrading, or reducing such degradation,caused by the ionic impurities diffusing into the light-emitting layer.

[0030] Furthermore, in the method of manufacturing the organicelectroluminescent device, it is preferable that the inorganic ionexchange material be disposed by ejecting liquid droplets, to form theinorganic ion exchange layer.

[0031] When done this way, it will be possible to precisely distributethe inorganic ion exchange material at the desired location, and thus,for example, selectively distribute the inorganic ion exchange materialcorresponding to the light-emitting layer's color.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032]FIG. 1 is a sectional side view of significant parts of an organicelectroluminescent device according to the present invention;

[0033]FIG. 2 is a schematic explaining a method of manufacturing theorganic electroluminescent device;

[0034]FIGS. 3A-3C are schematics of the processes subsequent to theprocess shown in FIG. 2;

[0035]FIG. 4 is a sectional side view of significant parts of anotherorganic electroluminescent device according to the present invention;and

[0036]FIG. 5 is a sectional side view of significant parts of stillanother organic electroluminescent device according to the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0037] Exemplary embodiments of the present invention are described indetail below.

[0038] (First Exemplary Embodiment)

[0039]FIG. 1 is a sectional side view showing significant parts of anorganic electroluminescent device according to a first exemplaryembodiment of the present invention. FIG. 1 shows the organicelectroluminescent device 1. The organic electroluminescent device 1 hasa transparent electrode 3 (a first electrode) and a cathode 4 (a secondelectrode) on a substrate 2 thereof, and has a functional layer 5between the transparent electrode 3 and the cathode 4, with the lightemitted in the functional layer 5 being emitted from the substrate 2side, which is referred to as a bottom emission type.

[0040] In the substrate 2, driving elements (not shown) composed of TFTelements, or various wiring lines, are formed on a transparentsubstrate, such as a glass substrate (not shown), and transparentelectrodes 3 are formed on the corresponding driving elements or variouswiring line via an insulating film or a flattening film.

[0041] The transparent electrodes 3 are patterned in correspondingsingle dot areas to be formed on the substrate 2, and are respectivelyconnected to the driving elements composed of TFT elements, or variouswiring lines. In the present invention, the transparent electrodes areformed of indium tin oxide (ITO).

[0042] An inorganic bank 6 and an organic bank 7 are formed around thetransparent electrode 3 to define a single dot area, and the functionallayer 5 is provided in a concave portion surrounded by the inorganicbank 6 and the organic bank 7.

[0043] Particularly, in the dot area that emits red or green light, thefunctional layer 5 includes a hole injection/transport layer 8 and alight-emitting layer 9, as shown in FIG. 1. Further, in the dot areathat emits green light, an electron injection/transport layer (notshown) is provided on the light-emitting layer 9 in addition to the holeinjection/transport layer 8 and the light-emitting layer 9.

[0044] The hole injection/transport layer 8 is formed of a materialobtained by adding an inorganic ion exchange material to an originalmaterial to form the hole injection/transport layer.

[0045] In other words, as the original material to form the holeinjection/transport layer, a dispersion solution of3,4-polyethylenedioxythiophene/polystylene sulfonic acid (PEDOT/PSS)[Brand name: “Bytron-p” made by Bayer AG], i.e., a dispersion solutionwhich is obtained by dispersing 3,4-polyethylenedioxythiophene inpolystyrene sulfonic acid as the dispersion medium, and dispersing theresultant again in water may be adequately used. Here, Na ions as ionicimpurities with a concentration close to hundreds of ppm is contained inthis formation material, and the Na ions may diffuse as mobile ions.

[0046] Accordingly, in the present exemplary embodiment, a dispersionsolution, which is obtained by adding an inorganic ion exchange materialto such material, is used.

[0047] The inorganic ion exchange material is composed of metal salt,such as metallic oxide, and includes the type that adsorbs positive ionsto trap and fixate these ions, the type that adsorbs negative ions totrap and fixate these ions, and the type that adsorbs both the positiveand negative ions to trap and fixate these ions.

[0048] The inorganic ion exchange material to trap and fixate positiveions may include antimony pentoxide (Sb₂O₅) hydrates (for example, IXE[registered trademark]-300 made by Toagosei. Co., Ltd.)), titaniumphosphate (for example, IXE [registered trademark]-400 made by Toagosei.Co., Ltd.), or zirconium phosphate (for example, IXE [registeredtrademark]-100 made by Toagosei. Co., Ltd.). Antimony pentoxide hydratesespecially have a high selective absorption to Na ions and are thussuitable as an inorganic ion exchange material added to the originalmaterial to form the hole injection/transport layer. The reason for thisis that many Na ions are included as the ionic impurities in theoriginal material to form the hole injection/transport layer aspreviously described, and they become mobile ions which may degrade thelight-emitting property in the light-emitting layer 9.

[0049] Further, the inorganic ion exchange material to trap and fixatenegative ions may include the hydrous bismuth oxide (for example, IXE[registered trademark]-500 made by Toagosei. Co., Ltd.), or leadphosphate hydroxide (for example, IXE [registered trademark]-1000 madeby Toagosei. Co., Ltd.). Since hydrous bismuth oxide especially have ahigh selective absorption to sulphate (SO₄ ⁻²) ions, it is suitably usedas an inorganic ion exchange material added to the original material toform the hole injection/transport layer together with the aforementionedantimony pentoxide hydrates. In other words, the original material toform the hole injection/transport layer uses polystyrene sulfonic acidas the dispersion medium. Thus, when Na ions are trapped and fixated inthe antimony pentoxide hydrates, free sulphate ions increase and thefree sulphate ions become mobile ions and diffuse, which may degrade thelight-emitting property of the light-emitting layer 9. Therefore, byadding the aforementioned hydrous bismuth oxide, the free sulphate ionsare trapped and fixated, making it possible to prevent the degrading ofthe light-emitting property of the light-emitting layer 9 or reducingsuch degradation.

[0050] The inorganic ion exchange material to adsorb both positive andnegative ions to trap and fixate these ions may include zirconium oxideor hydrous zirconium oxide, hydrous titanium oxide, and furthermore,substances in the antimony or bismuth system (for example, IXE[registered trademark]-600 or IXE [registered trademark]-633), which ismade by Toagosei. Co., Ltd.). When using such type, a simultaneoustrapping and fixation of both the Na ions included in the originalmaterial to form the hole injection/transport layer and the freesulphate ions can be expected.

[0051] Also, in the present exemplary embodiment, antimony pentoxidehydrates are used as an inorganic ion exchange material, and is added tothe original material to from the hole injection/transport layer,thereby forming a hole injection/transport layer 8.

[0052] As the material to form the light-emitting layer 9, a related artor known material capable of emitting fluorescent light orphosphorescence is used. In the present exemplary embodiment,particularly, the luminous wavelength bands corresponding to the threeprimary colors of light are used to achieve full color display. That is,three light-emitting layers (dots) including a light-emitting layercorresponding to red, a light-emitting layer corresponding to green, anda light-emitting layer corresponding to blue, constitute a pixel. Thelight-emitting layers emit light with grayscales, so that the organicelectroluminescent device 1 can perform a full color display.

[0053] As the specific material to form the light-emitting layer 9,polymeric materials, such as the polysilane system including(poly)-fluorene (PF) derivatives, (poly)-paraphenylenevinylene (PPV)derivatives, polyphenylene (PP) derivatives, polyparaphenylene (PPP)derivatives, polyvinylcarbazole (PVK) derivatives, polythiophenederivatives and polymethyl phenylsilane (PMPS) derivatives are suitablyused.

[0054] Further, materials obtained by doping the above-mentionedpolymeric materials with polymeric materials, such as perylene basedpigments, coumarin pigments and rhodamine pigments, or low molecularmaterials, such as rubrene, perylene, 9,10-diphenylanthracene,tetraphenylbutadiene, Nile red, coumarin 6, quinacridon can also beused.

[0055] The cathode 4 is formed to cover the entire pixel area, and isformed by sequentially laminating a Ca layer and an Al layer from thelight-emitting layer 9 side.

[0056] Further, a sealing layer 11 is formed on the cathode 4. Thesealing layer 11 can have a known construction that is formed by aprotective layer, an adhesive layer and a sealed substrate.

[0057] In order to manufacture the organic electroluminescent device 1having such a construction, TFTs or various wiring lines is first formedon a transparent substrate in the same way as in a related art or theconventional manner, and an interlayer insulating film or a flatteningfilm is then formed, thereby obtaining the substrate 2.

[0058] Next, an ITO film is formed on the substrate 2 by a vapordeposition method, and a transparent electrode 3 is formed bypatterning.

[0059] Subsequently, an inorganic bank 6 formed of SiO2 is formed on thesubstrate 2 so as to surround the transparent electrode 3, and anorganic bank 7 formed of resin is also formed on the inorganic bank 6,so that a concave portion 12 is formed in the transparent electrode 3,as shown in FIG. 2. Materials used for the organic bank 7 may includepolyimide or acrylic resin. Materials in which elemental fluorine isincluded in those materials in advance may also be used.

[0060] Next, as shown in FIG. 2, the wettability on the substrate inwhich the concave portion 12 is surrounded by the inorganic bank 6 andthe organic bank 7 is controlled by the consecutive plasma treatment ofoxygen plasma-CF4, and a hole injection/transport layer 8 is formedinside the concave portion 12 by a liquid droplet ejection method, suchas an ink jet method. Here, an inorganic ion exchange material (antimonypentoxide hydrates) added to the original material to form the holeinjection/transport layer as previously described, is used to form thehole injection/transport layer 8. However, this inorganic ion exchangematerial is powdered. If the grain size is not small enough, a liquiddroplet ejection head (an ink jet head) may get stuck. Thus, it ispreferred that the grain size be adjusted under a predetermined valueand then be used.

[0061] Specifically, for example, antimony pentoxide hydrate (IXE[registered trademark]-300 made by Toagosei. Co., Ltd.) is added to theoriginal material (a dispersion solution of PEDOT/PSS) to form the holeinjection/transport layer until it reaches 1 percent by weight, and isagitated for a predetermined period of time (for instance, 18 hours).Then, the obtained liquid is filtered through a filter with a mesh sizeof 1.0 μm. Subsequently, the obtained filtrate is filtered again,through a filter with a mesh size of 0.5 μm, whereby the powders withdiameters over 0.5 μm are removed from the material.

[0062] With the material made through this process, this material isselectively ejected as liquid droplets 8 a into the concave portion 12from a liquid droplet ejection head (ink jet head) 13, as shown in FIG.3A, and when this is continued, a hole injection/transport layer 8 isformed on the transparent electrode 3, as shown in FIG. 3B.

[0063] Next, as shown in FIG. 3C, a light-emitting layer 9 is formed onthe hole injection/transport layer 8 within the concave portion 12. Theliquid droplet ejection method (ink jet method) is also suitably adoptedto form the light-emitting layer 9. In other words, when forming thelight-emitting layer 9, each of the light-emitting layers for red, greenand blue must be made independently, but according to the liquid dropletejection method, the formation material for each of the light-emittinglayers is separately implanted simply at the desired location, whichmakes it possible to easily form each of the light-emitting layers.

[0064] Next, a Ca film is formed with the light-emitting layer 9 and theorganic bank 7 being covered therewith by a vapor deposition method inthe same way as in the related art or conventional manner, and an Alfilm is formed on the Ca film, thereby forming a cathode 4 of a Ca/Allayered structure. Particularly, in the case of the blue light-emittinglayer, an electron injection/transport layer may be formed using a maskwith the selective vapor deposition of LiF on the blue light-emittinglayer, but this is not described in detail below.

[0065] Thereafter, a protective layer and an adhesive layer are formedon the cathode 4, and further by adhering a sealed substrate, an organicelectroluminescent device 1 shown in FIG. 1 can be attained.

[0066] In the organic electroluminescent device 1 obtained as describedabove, an inorganic ion exchange material is added to the holeinjection/transport layer 8 to form it. Thus, mobile ions, such as Naions or sulphate ions in the material to form the holeinjection/transport layer, will be trapped and fixated by the inorganicion exchange material and will be kept confined inside the holeinjection/transport layer 8, thereby preventing the mobile ions fromdiffusing, or reducing such diffusion, into the light-emitting layer 9and shortening the lifespan, as a result of that the life extension canbe attained.

[0067] Further, by trapping and fixating the Na ions by the inorganicion exchange material and keeping the Na ions confined inside the holeinjection/transport layer 8, the Na ions can be prevented fromdiffusing, or such diffusion can be reduced, into the TFT element sideof the substrate 2, and characteristics of the TFT element can beprevented from being damaged or such damage can be reduced.

[0068] Moreover, for example, even when the In ions or Sn ions in thetransparent electrode 3 diffuses, they can be trapped and fixated in thehole injection/transport layer 31 with the inorganic ion exchangematerial and can be prevented from diffusing, or such diffusion can bereduced, into the light-emitting layer 9. As a result, the degrading ofthe light-emitting property, i.e., shortening of the lifespan can bereduced or prevented.

EXPERIMENTAL EXAMPLE

[0069] A transparent electrode formed of ITO is formed on a substrate 2,and on the transparent electrode, a material (a material obtained fromfiltering twice and adjusting the diameter of the inorganic ion exchangematerial) used to form a hole injection/transport layer 8 is used toform a film by a spin coating method, thereby forming a holeinjection/transport layer.

[0070] Next, a light-emitting material that emits green color light isapplied on the hole injection/transport layer by a liquid dropletejection method, thereby forming a light-emitting layer.

[0071] Thereafter, a Ca film and an Al film are respectively formed onthe light-emitting layer in this order by a vapor deposition method toform a cathode composed of a Ca/Al layered structure, and after sealing,the experimental example of the organic electroluminescent deviceaccording to the present invention is attained.

[0072] For comparison, a hole injection/transport layer formed of theoriginal material without the addition of an inorganic ion exchangematerial was formed, and the rest is manufactured in the same way as inthe exemplary embodiment, so that the organic electroluminescent deviceas a comparative example was attained.

[0073] After measuring the lifespan of each of these organicelectroluminescent devices formed as previously described, the exemplaryembodiment had a lifespan 1.6 times longer than the comparative example,and it could be confirmed that, by adding the inorganic ion exchangematerial, the life extension of light-emitting elements can beaccomplished.

[0074] Further, the lifespan measured here was the period of time forthe luminance to drop to half of its initial value. Also, the results ofthe increase in a drive voltage measured until the luminance droppeddown to its half showed that the exemplary embodiment was suppressed by0.68 times from the experimental example.

[0075] (Second Exemplary Embodiment)

[0076]FIG. 4 is a sectional side view showing significant parts of anorganic electroluminescent device according to a second exemplaryembodiment of the present invention. FIG. 4 shows the organicelectroluminescent device 20. A significant difference between theorganic electroluminescent device 20 shown in FIG. 4 and the organicelectroluminescent device 1 shown in FIG. 1 is that, in the organicelectroluminescent device 20 shown in FIG. 4, an inorganic ion exchangelayer 22 is formed between a hole injection/transport layer 21 and alight-emitting layer 9.

[0077] In other words, in the organic electroluminescent device 20 shownin FIG. 4, the hole injection/transport layer 21 is formed with only theoriginal material to form the hole injection/transport layer, somewhatdifferent from the hole injection/transport layer 8 shown in FIG. 1.Accordingly, the hole injection/transport layer 21 formed of theoriginal material to form the hole injection/transport layer willcontain many Na ions as its ionic impurities as described above, andfrom this, these Na ions easily diffuse as mobile ions.

[0078] However, in the present exemplary embodiment, the inorganic ionexchange layer 22 is formed between the hole injection/transport layer21 and the light-emitting layer 9. The inorganic ion exchange layer 22is formed of the inorganic ion exchange material as mentioned above, andfor instance, is formed by mixing this inorganic ion exchange materialwith conductive resin, arranging the mixed inorganic ion exchangematerial on the hole injection/transport layer 21 by a liquid dropletejection method, thereby forming a film. Depending on the types of theinorganic ion exchange material, the vapor deposition method can be usedto form a film.

[0079] The light-emitting layer 9 is formed on the inorganic ionexchange layer 22, and further a cathode 4 is formed on thelight-emitting layer 9. Further, in the same manner as in the firstexemplary embodiment, an electron injection/transport layer (not shown)is formed on the blue light-emitting layer. Moreover, a sealing layer 11is formed on the cathode 4, thereby forming the organicelectroluminescent device 20.

[0080] In the organic electroluminescent device 20 having the aboveconstruction, the inorganic ion exchange layer 22 is provided betweenthe hole injection/transport layer 21 and the light-emitting layer 9.Thus, when the Na ions that are ionic impurities existing, especially,in the hole injection/transport layer 21 become mobile ions and diffuse,they can be trapped and fixated by the inorganic ion exchange layer 22.Accordingly, the light-emitting property can be prevented fromdegrading, or such degradation can be reduced, due to the diffusion ofNa ions into light-emitting layer 9, for example, the lifespan can beprevented from shortening or such shortening can be reduced.

[0081] Further, for example, even when Sn ions in the transparentelectrode 3 diffuse, these ions will be trapped and fixated and beprevented from diffusing, or such diffusion can be reduced, into thelight-emitting layer 9 and degrading the light-emitting property.

[0082] (Third Exemplary Embodiment)

[0083]FIG. 5 is a sectional side view showing significant parts of anorganic electroluminescent device according to a third exemplaryembodiment of the present invention. FIG. 5 shows the organicelectroluminescent device 30. A significant difference between theorganic electroluminescent device 30 shown in FIG. 5 and the organicelectroluminescent device 20 shown in FIG. 4 is that, in the organicelectroluminescent device 30 shown in FIG. 5, an inorganic ion exchangelayer 32 is formed between a light-emitting layer 9 and an electroninjection/transport layer 31.

[0084] The inorganic ion exchange layer 32 is formed of the inorganicion exchange material described in the first exemplary embodiment,similar to the inorganic ion exchange layer 22 shown in FIG. 4. In otherwords, for example, the inorganic ion exchange layer is formed by mixingthis inorganic ion exchange material with conductive resin, andarranging the mixed inorganic ion exchange material on a holeinjection/transport layer 21 by a liquid droplet ejection method.Depending on types of the inorganic ion exchange material, the vapordeposition method can also be used to form a film.

[0085] An electron injection/transport layer 31 is provided when theblue light-emitting layer is formed of, especially, a polymericmaterial, and is formed from the selective vapor deposition of LiF ontothe light-emitting layer (blue light-emitting layer) 9 with a mask. Theelectron injection/transport layer 31 formed of LiF is for efficientinjection/transport of electrons from the cathode 4 of Ca/Al formedthereon to the light-emitting layer 9.

[0086] Further, if the electron injection/transport layer 31 comes indirect contact with the light-emitting layer 9 in the same way as in therelated art or conventional manner, the Li ions in the electroninjection/transport layer 31 will become mobile ions and diffuse intothe light-emitting layer 9. Then, while these Li ions stay in thesurface of the light-emitting layer 9, i.e., the interface with theelectron injection/transport layer 31, they will function to attract theelectrons from the cathode 4 to the light-emitting layer 9, and thiswill improve the injection property/transportability of electrons.

[0087] However, as some time elapses, the Li ions will diffuse into thecenter of the light-emitting layer 9, and the function to attractelectrons will diminish, whereas the light-emitting efficiency of thelight-emitting layer 9 or the luminance thereof will degrade, eventuallyshortening the lifespan.

[0088] Therefore, in the present exemplary embodiment, the inorganic ionexchange layer 32 is formed between the light-emitting layer 9 and theelectron injection/transport layer 31 as described above. From thisformation of the inorganic ion exchange layer 32, the Li ions from theelectron injection/transport layer 31 will be trapped and fixated in theinorganic ion exchange layer 32, and this allows the light-emittingproperty to be prevented from degrading, or such degradation can bereduced, due to diffusion of the Li ions into the light-emitting layer9, for example or the lifespan to be prevented from shortening or suchshortening can be reduced. Also, even when the Ca ions in the cathode 4diffuse, they can be trapped and fixated and be prevented fromdiffusing, or such diffusion can be reduced, into the light-emittinglayer 9, thereby preventing or reducing degrading of the light-emittingproperty.

[0089] In the present exemplary embodiment, it is also preferred thatthe inorganic ion exchange layer 32 be formed by the liquid dropletejection method (ink jet method). By adopting the liquid dropletejection method, the inorganic ion exchange material can be selectivelyor precisely disposed only on the blue light-emitting layer.Accordingly, reliability, such as the lifespan characteristics in theblue light-emitting layer, can be satisfactorily secured. Also, whenadopting the liquid droplet ejection method, it can be conducted bymixing the inorganic ion exchange material with conductive resin, anddissolving it in a suitable solvent or dispersing in a suitabledispersion medium.

[0090] In the organic electroluminescent device 30 having the aboveconstruction, the inorganic ion exchange layer 32 is formed between thelight-emitting layer 9 and the electron injection/transport layer 31.Thus, the Li ions from the electron injection/transport layer 31 will betrapped and fixated in the inorganic ion exchange layer 32, which willprevent or reduce the Li ions from diffusing into the light-emittinglayer 9 and degrading the light-emitting property, and for instance,shortening the lifespan. Even when the Ca ions in the cathode 4 diffuse,they will be trapped and be prevented from diffusing, or such diffusioncan be reduced, into the light-emitting layer 9, and degrading thelight-emitting property can be reduced or prevented.

[0091] The present invention is not limited to the first, second andthird exemplary embodiments, and various alterations can be made as longas they do not depart from the scope of the present invention.

[0092] For example, the hole injection/transport layer 8 as the carrierinjection/transport layer was formed by adding an inorganic ion exchangematerial in the first exemplary embodiment, but when forming an electroninjection/transport layer with a polymeric material, the metallicion-trapping materials mentioned above may be added to the material toform the electron injection/transport layer.

[0093] When done this way, by trapping and fixating the metallic ions(ionic impurities) from the cathode 4 or the metallic ions (ionicimpurities) existing in the electron injection/transport layer by aninorganic ion exchange material to confine the ions in an electroninjection/transport layer, the diffusion of these metallic ions (ionicimpurities) into the light-emitting layer 9 which degrades thelight-emitting property, such as the lifespan, can be reduced orprevented.

[0094] Also, the inorganic ion exchange material may be directly addedto the material to form the light-emitting layer and this may be used toform the light-emitting layer. Then, even if the metallic ions diffusefrom the hole injection/transport layer which is the carrierinjection/transport layer or the electron injection/transport layer, andfurther from the transparent electrode 3 or the cathode 4, they can betrapped and fixated by the inorganic ion exchange material, making itpossible to reduce or prevent the light-emitting property from degradingdue to the metallic ions.

[0095] Further, in the second and third exemplary embodiments, theinorganic ion exchange layer 22 (32) was provided only either betweenthe hole injection/transport layer 21 and the light-emitting layer 9 orbetween the light-emitting layer 9 and the electron injection/transportlayer 31. However, the inorganic ion exchange layer 22 and the inorganicion exchange layer 32 may be provided on both sides.

[0096] Further, in the above exemplary embodiments, a polymeric materialis used as the material to form the light-emitting layer 9, but a lowmolecular material may also be used to form the light-emitting layer 9.In that case, it is preferred that the electron injection/transportlayer is provided in all of the light-emitting layers, not just on theblue light-emitting layer, and that an inorganic ion exchange layer isprovided between every light-emitting layer and electroninjection/transport layer.

[0097] Moreover, the exemplary embodiments have described about applyingthe present invention to a bottom emission type organicelectroluminescent device, but the present invention is not limited tothis type, and can also be applied to a so-called top emission typeorganic electroluminescent device, where light is emitted from theopposite side of the substrate.

[0098] The organic electroluminescent device of the present invention aspreviously described can be suitably used as a display for portableinformation processors, such as word processors and personal computers,or electronic apparatuses, such as portable phones and wristwatch-typeelectronics, for example.

What is claimed is:
 1. An organic electroluminescent device, comprising:a first electrode; a second electrode; and a functional layer having atleast a light-emitting layer between the first electrode and the secondelectrode, at least a part of the functional layer being formed by usinga functional material with an inorganic ion exchange material.
 2. Theorganic electroluminescent device according to claim 1, the functionallayer having a carrier injection/transport layer, and the functionallayer formed by adding the inorganic ion exchange material being a holeinjection/transport layer functioning as the carrier injection/transportlayer.
 3. The organic electroluminescent device according to claim 1,the inorganic ion exchange material being antimony pentoxide hydrate. 4.The organic electroluminescent device according to claim 1, thefunctional layer formed by adding the inorganic ion exchange materialbeing the light-emitting layer.
 5. The organic electroluminescent deviceaccording to claim 1, the functional layer having a carrierinjection/transport layer, and the functional layer formed by adding theinorganic ion exchange material being an electron injection/transportlayer functioning as the carrier injection/transport layer.
 6. Anorganic electroluminescent device, comprising: a first electrode; asecond electrode; a functional layer having at least a light-emittinglayer between the first electrode and the second electrode; and aninorganic ion exchange layer formed of an inorganic ion exchangematerial provided between the first electrode and the second electrode.7. The organic electroluminescent device according to claim 6, thefunctional layer having a hole injection/transport layer between thefirst electrode and the light-emitting layer, and the inorganic ionexchange layer being provided between the hole injection/transport layerand the light-emitting layer.
 8. The organic electroluminescent deviceaccording to claim 6, the functional layer having an electroninjection/transport layer between the second electrode and thelight-emitting layer, and the inorganic ion exchange layer beingprovided between the electron injection/transport layer and thelight-emitting layer.
 9. A method of manufacturing an organicelectroluminescent device that includes a functional layer having alight-emitting layer and a carrier injection/transport layer between afirst electrode and a second electrode, the method comprising: adding aninorganic ion exchange material to a functional material; and forming atleast a part of the functional layer using the obtained functionalmaterial.
 10. The method of manufacturing an organic electroluminescentdevice according to claim 9, further including disposing the functionalmaterial with the addition of the inorganic ion exchange material byejecting liquid droplets to form the functional layer.
 11. A method ofmanufacturing an organic electroluminescent device that includes afunctional layer having at least a light-emitting layer between a firstelectrode and a second electrode, the method comprising: disposing aninorganic ion exchange material between the first electrode and thesecond electrode to form an inorganic ion exchange layer.
 12. The methodof manufacturing an organic electroluminescent device according to claim11, further including disposing the inorganic ion exchange material byejecting liquid droplets to form the inorganic ion exchange layer.